Author + information
- Received March 6, 1992
- Revision received July 15, 1992
- Accepted July 21, 1992
- Published online February 1, 1993.
- Chunguang Chen, MD∗,
- Dietmar Koschyk, MD,
- Carsten Brockhoff, MD,
- Sören Heik, MD,
- Christian Hamm, MD,
- Walter Bleifeld, MD, FACC† and
- Wolfram Kupper, MD
- ↵∗Current address and address for correspondence: Chunguang Chen, MD, Non-Invasive Cardiac Laboratory, Massachusetts General Hospital, Zero Emerson Place, 2F, Boston, Massachusetts 02114.
Objectives. This study was designed lo examine the accuracy of proximal accelerating flow calculations in estimating regurgitant flow rate or volume in patients with different types of mitral valve disease.
Background. Flow acceleration proximal to a regurgitant orifice, observed with Doppler color flow mapping, is constituted by isovelocity surfaces centered at the orifice. By conservation of mass, the flow rate through each isovelocity surface equals the flow rate through the regurgitant orifice.
Methods. Forty-six adults with mitral regurgitation of angiographic grades I to IV were studied. The proximal accelerating flow rate (Q) was calculated by: Q = 2 πr2·Vn, where πr2is the area of the hemisphere and Vn is the Nyquist velocity. Radius of the hemisphere (r) was measured from two-dimensional or M-mode Doppler color recording. From the M-mode color study, integration of accelerating flow rate throughout systole yielded stroke accelerating flow volume and mean flow rate. Mitral regurgitant flow rate and stroke regurgitant volume were measured by using a combination of pulsed wave Doppler and two-dimensional echocardiographic measurements of aortic forward flow and mitral inflow.
Results. The proximal accelerating flow region was observed in 42 of 46 patients. Maximal accelerating flow measured from either two-dimensional (372 ± 389 ml/s) or M-mode (406 ± 421 ml/s) Doppler color study tended to overestimate the mean regurgitant flow rate (306 ± 253 ml/s, p < 0.05). Mean Doppler accelerating flow rate correlated well with mean regurgitant flow rate (r = 0.95, p < 0.001), although there was a tendency toward slight overestimation of mean regurgitant flow by mean accelerating flow in severe mitral regurgitation. However, there was no significant difference between the mean accelerating flow rate (318 ± 304 ml/s) and the mean regurigitant flow rate (306 ± 253 ml/s, p = NS) for all patients. A similar relation was found between accelerating flow stroke volume (78.27 ± 62.72 ml) and regurgitant flow stroke volume (76.06 ± 59.76 ml/) (r = 0.95, p < 0.001). The etiology of mitral regurgitation did not appear to affect the relation between accelerating flow and regurgitant flow.
Conclusions. Proximal accelerating. flow rate calculated by the hemispheric model of the isovelocity surface was applicable and accurate in most patients with mitral regurgitation of a variety of causes. There was slight overestimation of regurgltant flow rate by accelerating flow rate when tbe regurgitant lesion was more severe.
☆ This paper was presented in part at the 64th Annual Scientific Sessions of the American Heart Association, Anaheim, California, November 1991 and in part at the Annual Scientific Session of the American College of Cardiology, Dallas, Texas, April 1992. This study was supported, in part by a research grant of the German Association of Cardiovascular Research, Bad Nauheim, Germany.
- Received March 6, 1992.
- Revision received July 15, 1992.
- Accepted July 21, 1992.